Liquid fuel for internal combustion engines



Patented Sept. 22, 1942 LIQUID FUEL FOR INTERNAL COMBUSTION ENGINESVaman R.

Autoxygen, llnc., New York, N. Y.,

of New York No Drawing.

11 Claims.

Kokatnur, New York, N. Y., assignor to v a corporation ApplicationSeptember 20, 1938, Serial No. 230,815

crease the combustion quality of liquid fuels' which have a high flashpoint and a high boiling point and which are used in Diesel engines orother types of engines where the principle of injection in contrast withthat of carburetion is used.

Another object of the invention is to increase the cetene value of thefuels so that unit for unit they can stand higher compression and givegreater power by combustion.

A further object of the invention is to produce better combustion sothat the interior of the combustion chamber will be free from carbondeposits and the exhaust will be relatively freer from carbon monoxide.

A still further object of the invention is to produce a fuel of highignition quality and yet relatively no more corrosive to the enginewalls than the normal fuel itself.

It has been established by experiments that the ideal fuel for use inengines of the Diesel type,

which operate on injected fuel, is cetene, a relatively heavy andnon-volatile hydrocarbon oil containing between 16 and 18 carbon atoms.Pure cetene, however, is too expensive and dimcult to produce forpractical use, and as a result, there have been many attempts made todevise treatments for other similar fuels to increase their cetenerating. Such treatments are known as doping" and comprise adding to thefuel oil compounds which contain oxygen in excess of the amountnecessary for their'own combustion.

The compounds more commonly used for this purpose are various nitrocompounds such as ethyl nitrate, amyl nitrate, and even nitroglycerineand picric acid, which is tri-nitrophenol.

Some of these nitro compounds are reasonably satisfactory for thispurpose but their cost is prohibitive. Other nitro compounds such aspicric acid and nitroglycerine are dangerousto handle, not to speak oftheir expensive price. All nitro compounds, dangerous or-otherwise,produce during combustion nitric oxide gas which in combination with thewater of the combustion produces the well known nitric acid. It isneedless to speak further of the corrosiveness of this acid which is thestrongest known to chemistry.

1 am aware that other nitrogen compounds such as nitrites as well asamino compounds are used for this purpose either for doping or forstabilizing. I am also aware that certain organic peroxides have beensuggested for doping liquid fuels for use in the injector type ofinternal combustion engines.

The suggested compounds in the prior art are benzoyl peroxide, acetoneperoxide, tetralene peroxide, naphthalene peroxide, and the peroxidesproduced in the Diesel oils themselves, which really are the ozonides,amylene peroxide, hydrogen peroxide and several peracid salts such asperborates, percarbonates, etc. These peroxides, while they have shown acertain usefulness in the raising of the cetene values, have found nopractical use.

Substantially all of the above mentioned compounds sufier from manyserious drawbacks for purposes of doping" the liquid fuels. First,almost all of them are substantially insoluble in all oily materialssuch as Diesel fuels, vegetable, or animal oils, fatty acids, etc.Solubility to the extent of a small fraction of 1% is of no consequence,since in practice the dopes have to be used in proportions ofapproximately 1% to 5% to bring about practical results.

The second serious drawback of the suggested compounds is that with theexception of benzoyl peroxide, all others are relatively too unstable tobe used as dopes" in these fuels.

Thirdly, most of these compounds such asbenzoyl peroxide, andnaphthalene peroxide, etc., are sensitive both to heat and compressionand consequently decompose or explode prematurely before they areinjected with the fuel in the combustion chamber. Due to their lack ofsolubility, the unit injected fuel does not contain auniform homogeneousamount of this dope. This results in lack of uniformity in ignition.

According to the practice of this invention, it has been found that mostof these drawbacks may be avoided and a fuel of high ignition quality,that is, high, cetene value, may be prepared by using as dopes organicperoxides of the acyl or alkyltype, and particularly those that areoilor fat-soluble.

The suitable peroxides for this purpose are those of butyricacid,caproic acid, lauric acid, myristic acid, palmitic acid, stearic acid,etc. Although the above are peroxides of the even carbon atom acids, itis to be understood that peroxides of the odd carbon atoms, as well asthose that contain a ring and an attached side chain of no less than 5carbon atoms, are understood to be included within the scope of theinvention.

The higher fatty acids containing 10 or more carbon atoms, straightchain, branch chain, ring with a side chain, saturated or unsaturated,odd

or even carbon atoms, are to be preferred. It is to be understood,however, that alkyl peroxides containing 6 or more carbon atoms,saturated or unsaturated, odd or even carbon atoms, are definitely.within the scope of the invention.

The acyl or alkyl peroxides used for doping" in this invention are allsoluble in liquid fuels to a suflicient extent so that 1% to may bedissolved in. these fuels. Secondly, they are quite stable and lose buta small portion of their value when stored as doped fuels for a periodof at least about a year. Thirdly, they are not at all sensitive to heatand pressure and are substantially non-explosive under practical workingconditions. For this reason they do not decompose or explode prematurelyand due to their solubility do not produce non-uniform ignition.

The organic peroxides have another great advantage although in commonwith all other organic peroxides. and that is that in a normalproduction of combustion they are no more corrosive to the engine thanthe straight "undoped" fuels.

This use of organic peroxides in doping produces considerable unexpectedbehavior, one instance of which is that in homologous series, the riseof cetene value, instead of being proportional to the available oxygenof the peroxide, seems to increase first in inverse proportion to theperoxidic oxygen content, apparently reaches a peak, and then falls offas the number of carbon atoms increases.

The peroxides of lower carbon atoms do not increase the cetene value inproportion to the peroxidic'oxygen they contain. The peroxidescontaining from 10 carbon atoms upward seem to have the optimum effectfor this purpose and this is the reason why I prefer to use peroxides ofacids or alkyls containing 10 or more carbon atoms, although thosecontaining as few as 6 carbon atoms may be used. The optimum for thisseems to lie somewhere between 16 to carbon atoms, although thisincrease over 10, 12 or 14 carbon atoms is not appreciably very large.This is certainly a very strange behavior and quite unexpected accordingto principles of stoicheiometry.

According to the practice of this invention,. any suitable oleaginouscompound may be used as a base. The usual requirements for suitabilityare non-volatility, water insolubility, high flash point and highboiling point. Either a mineral, vegetable, or animal oil may be used.Hydrocarbon oils or their derivatives are particularly suitable,especially their ester derivatives. To this oil base is added about 1%to 1.5% of a suitable peroxidic compound of the above specified types,and the resulting solution is used as the fuel.

The cetene values of the liquid fuel, particularly of the Diesel type,are increased by my invention from to 50 units depending upon theoriginal cetene value of the fuel. This is an extraordinary increasecompared with the cetene increase as found byprior doping with organicperoxides or the nitro compounds.

In prior practice whether a nitro compound is used or an organicperoxide of the type mentioned above, the cetene increase has not beenany more than 10 to 20 points by the addition of 1% to 1/ of the dopes.Thus acetone peroxide increases the cetene only 10 points. Tetraleneperoxide increases the cetene value about 14 points, while with nitrocompounds it also increases about 14 points.

According to this invention, when the fuel is doped with 1 to 156% of asuitable peroxide, the cetene value rises 30 to 50 points when theoriginal cetene value is lower than 30. when the original cetene isbetween 30 to 50, then the rise is between 40 to 20 respectively. Andwhen the original cetene is above 50, the increase may be only 20, or insome cases may be even lower.

The acyl peroxides of the saturated acids increase the cloud point aswell as the pour point of the fuel. This, of course, in some cases isundesirable, and in order to avoid this particular drawback some mutualsolvent such as ether. acetone or lower hydrocarbons may be used. Theperoxides of unsaturated acids are normally liquids at room temperatureand are soluble in much larger proportion without in any way affectingthe cloud or the pour point.

In speaking of the peroxides of the unsaturated acids, there is meantthe true acyl peroxides and not peroxides or ozonides produced by theaddition of oxygen at the point of the double or treble bonds. Theperoxides produced from unsaturated compounds by the addition of oxygenat the double or treble bonds are normally solid and gummy and are notto be confused with the peroxides used in this invention.

Since certain changes in carrying out the above process, and certainmodifications in the composition which embody the invention may be madewithout departing from its scope, it is intended that all mattercontained in the above description shall be interpreted as illustrativeand not in a limiting sense. n

It is to be understood also that the following claims are intended tocover all of the generic and specific features of the invention asherein described, and all statements of the scope of the invention whichas a matter of language might be said to fall therebetween.

Having described my invention, what I claim as new and desire to secureby Letters Patent is:

1. A liquid fuel suitable for internal combustion engines of the Dieseltype, comprising a nonvolatile oleaginous compound and a peroxidiccompound selected from the group of peroxidic compounds consisting ofonly such alkyl peroxides -and acyl peroxides as are soluble in saidoleaginous compound and contain at least 6 carbon atoms in the radical.

2. A liquid fuel suitable for internal combustion engines of the Dieseltype, comprising an organic, water-insoluble hydrocarbon compound or itsderivatives, and a peroxidic compound selected from the group ofperoxidic compounds consisting of only such alkyl peroxides and acylperoxides as are soluble in said hydrocarboncompound and contain atleast 6 carbon atoms in the radical.

3. A liquid fuel suitable for internal combustion engines of the Dieseltype, comprising a hydrocarbon or'its ester derivatives, and a peroxidiccompound selected from the group of peroxidic compounds consisting ofonly such alkyl peroxides and acyl peroxides as are soluble in saidhydrocarbon compound and contain at least 3 carbon atoms in the radical.

4. A liquid fuel suitable for internal combustion engines of the Dieseltype, comprising an oil of mineral origin and a true peroxidic compoundselected from the group of peroxidic compounds consisting of only suchalkyl peroxides and acyl peroxides as are soluble in said oil andcontain at least 6 carbon atoms in the radical.

5. A liquid fuel suitable for internal combustion engines of the Dieseltype, comprising an oil or vegetable origin and a true peroxidlccompound selected from the group of peroxidic compounds consisting ofonly such alkyl peroxides and acyl peroxides as are soluble in said oiland contain at least 6 carbon atoms in the radical.

6. A liquid fuel suitable for internal combustion en ines of the Dieseltype, comprising an oil of animal origin and a true ozonidic peroxidiccompound selected from the group of peroxldlc compounds consisting ofonly such alkyl peroxides and acyl peroxides as are soluble -in said oiland contain at least 6 carbon atoms in the radical.

7. A liquid fuel suitable for internal combustion engines, particularlyof the Diesel type,'comprising an organic combustible material of highflash and high boiling point and a true peroxidic compound of fattyacids containing at least 10 carbon atoms, which is soluble in the saidoil.

8. A liquid fuel suitable for internal combustion engines, particularlyof the Diesel type, comprising an organic combustible material of highflash and high boiling point, and a true peroxidic compound of the alkyltype containing at leafit 10 carbon atoms, and which is soluble in thesaid oil.

9. A liquid fuel suitable for internal combustion engines, particularlyof the Diesel type, comprising an'crganic combustible material of highflash and high boiling point, and a true peroxidic compound of analicyclic acid, containing at least 10 carbon atoms, and which issoluble in said oil.

10. A liquid fuel suitable for internal combustion engines, particularlyof the Diesel type, comprising an organic combustible material of highflash and high boiling point. and a true peroxidic compound of alicyclicfatty acid containing at least 10 carbon atoms,- and which is soluble insaid oil.

11. A Diesel fuel containing lauroyl peroxide in sufficient amount toincrease the cetane number of the fuel base.

VAMAN R. KOKATNUR.

CERTIFICATE OF CORRECTION. Patent No. 2,296,558- September 22,.19LL2.

VAMAN R. KOKATNUR.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 5,first column, line 8, claim 6, strike out the word "ozonidic"; and thatthe said Letters Patent should be read with this correction therein thatthe same may conform to the record of the case in the Patent Office.

Signed and sealed this 2J.|.th day of November, A. D. 19142.

Henry Van Aredale, (Seal) 7 Acting Commissioner of Patents.

